This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. C. elegans as a model organism is well suited for studies in aging due to its short life span and easily controlled mating. The Jakobs lab has worked extensively on C. elegans and aging, most recently working on the role of oxidative stress. They, with other have developed the OxICAT system for mapping the redox active thiol proteome. Their conclusions show that while oxidative stress and aging both lead to comparable levels of reversibly oxidized cysteine residues, target proteins are different. However, their current methods can only map cysteines oxidized to disulphides and not cysteines oxidized to sulfunic or sulfonic acids. In conjunction with the Jakobs lab, we propose to use Sulfur XANES to map the total sulfur oxidation state and the amount of irreversible sulfur oxidation that happens as a result of the aging process compared to that of oxidative stress.